The invention relates to munitions and firearms.
This invention has particular, but not exclusive, application providing operational safety improvements to barrels of the type having a plurality of projectiles stacked axially within the barrel in sealing engagement therewith together with discrete propellant charges which are selectively ignitable for propelling the projectiles sequentially through the muzzle of the barrel and the sealing engagement between projectiles and barrel being such as to prevent rearward travel of the ignited propellant charge to trailing propellant charges. Such barrels will be referred to hereinafter as of the type described.
This invention has particular application to munitions and firearms inventions as described in my earlier International Patent Applications Nos. PCT/AU94/00124 and PCT/AU96/00459 which describe a wedging action between the sealing portion and an anvil portion of a projectile which effects a seal to prevent the products of combustion of the propellant charge for a leading projectile leaking to the next adjacent unfired propellant charge and igniting same.
During testing of prototypes made according to the abovementioned inventions concern has been raised regarding the possibility of a malfunction occurring such as a misfiring or a xe2x80x9chang firexe2x80x9d or like. While no jamming of projectiles has been experienced it is considered that this possibility needs to be minimised. The present system operates at about 40,000 psi chamber pressure but higher pressures in the order of 60,000 psi plus may be utilised.
It is envisaged that a misfire may occur either by a projectile jamming in the barrel or by the propellant for a trailing projectile being ignited prior to the propellant associated with a leading projectile.
This invention seeks to eliminate or alleviate misfiring and/or to alleviate any serious consequences in the event of a misfire occurring.
With the foregoing in view, this invention in one aspect resides broadly in a method of minimising misfiring or alleviating their consequences in a barrel of the type described including:
forming at least each trailing projectile with a sealing portion extending about a tapered anvil portion and moveable therealong for expansion into sealing engagement with the barrel bore, and
providing disengagement means for operatively disengaging the sealing portion from the anvil portion in response to ignition of the propellant charge associated with the projectile.
The method may be suited only to trailing projectiles to provide a forward bypass path for ignited propellant for alleviating the effect of a hang fire. Alternatively the method may be applied to each projectile including the leading projectile to enable effective discharge of projectiles loaded with high barrel engaging forces.
In the case of application of the method to trailing projectiles only, the disengagement means may be constituted by an anvil extension in the form of a spine placing the trailing anvil in columnar relationship with the adjacent leading projectile thereby increasing the resistance to forward movement of the tailing anvil portion and enabling the sealing portion to move forward along the anvil portion for operative disengagement therefrom.
The disengagement permits products of combustion of the trailing propellant charge to pass beyond the sealing portion to the leading propellant charge so as to ignite same and cause the leading projectile to be fired to free the barrel path for the trailing projectile. This may occur as a very quick chain-like reaction causing all projectiles ahead of the misfired propellant charge to be discharged.
For this purpose the sealing portion and the anvil portion of the trailing projectile or projectiles are of such form that the increased resistance to movement of a combined leading projectile and trailing projectile, upon ignition of the trailing projectile""s propellant charge, permits the trailing sealing portion to accelerate more quickly than the trailing anvil portion to create a bleed passage about or through the trailing sealing portion for combustion gases to pass therethrough and ignite the leading propellant charge.
The extension of the anvil portions may be rear or front extensions or both, with the extension being in continuous abutting relationship throughout the barrel to form a compression resistant column positively locating the respective anvil portions in the barrel.
Maximum chamber pressure will be reached prior to commencement of the bleed past the sealing portion. As a result the sealing portion of the trailing projectile will be forced forward until the combustion products bleed towards the leading projectile. Because of the slight time delay that occurs between the ignition of the propellant of the following projectile and the subsequent sympathetic ignition of the propellant of the leading projectile, it is unlikely that the resultant chamber pressure will exceed a reasonable allowable maximum.
The result should be that both projectiles will leave the barrel normally except that the sealing portion of the trailing projectile may separate from its anvil. Preferably the sealing portion is in the form of a malleable nose part slidable along a centrally located anvil extension and having a conical cavity extending in from an open rear end and in which the conical shaped anvil portion is located.
Alternatively in the case of application of the method to trailing projectiles only, the disengagement means may be constituted by a pressure sensitive leverage system connected between the anvil portion and the sealing portion which is normally inoperative so as not to affect the operation of the projectile but which operates when pressures in the barrel behind the projectile increases beyond a safe operating pressure to lever the sealing portion along the anvil portion to a disengaged position.
The pressure sensitive leverage system may be used with projectiles having forward or rearward diverging wedge surfaces between the anvil portion and the sealing portion. Suitably the pressure sensitive leverage system includes an actuator mounted on the rear end face of the projectile and preferably it is in the form of a collapsible plate which normally bears against the end face for firing in abutting relationship thereto but which upon being subject to extreme pressures distorts to provide movement to actuate the leverage system.
In the case of application of the method to a leading and/or trailing projectiles, the disengagement means may be constituted by a hammer member supported for free forward movement into a cavity formed in the exposed rear end of the anvil portion such that the hammer member is driven forward upon ignition of the associated propellant charge to impart its energy to the anvil portion by impact so as to jolt the anvil portion from operative sealing engagement with the sealing portion.
The effect of this will be to assist in instantly freeing the anvil portion to minimise any chance of jamming of the projectile previously wedged in the barrel. Furthermore in the case of a trailing projectile the freeing of the anvil portion from the sealing portion will provide a bleed passage as previously described for ignition in a trailing projectile to pass forwards and ignite the propellant charge of a remaining leading projectile.
It is preferred that the leading or each projectile include a tapered sealing portion in the form of a malleable band extending about a complementary tapered anvil portion such that forward movement of the anvil portion relative to the sealing portion operatively disengages the anvil portion therefrom.
The hammer member may constitute a major or minor portion of the projectile either by bulk or weight. Preferably the cavity in which the hammer member is supported is a blind cavity formed such that in operation, the hammer strikes the end wall of the blind cavity. However, if desired the cavity may extend forwardly through the projectile and various forms of obstructions may be used to impede movement of the hammer through the cavity. The obstructions may be a forward narrowing of the cavity or abutments protruding in from the wall of the cavity.
In one form the hammer is a relatively large diameter cylindrical body sealably and slidably supported in a correspondingly shaped cavity and moveable to a home or impacted position against the end wall of the cavity and at which the cavity is substantially filled by the hammer.
The hammer may be formed from the same material as the anvil portion or it may be formed from a different material such as a material having a different density or a different malleability, the particular combination of physical sizes, configurations and characteristics being selected to suit the purpose of the projectile.
In another aspect this invention resides broadly in a barrel of the type described, wherein:
each trailing projectile has a sealing portion extending about a tapered anvil portion and arranged in sealing engagement with the barrel bore and moveable forwardly therealong for operative freeing from the anvil portion;
a spine extends from each anvil portion placing the anvil anvil portions in columnar relationship with the barrel, and
the rear part of each sealing projectile is exposed too their respective propellant charges for forward propulsion relative to the anvil portion about which they extend when forward movement of such anvil portions is resisted.
In a further aspect this invention resides broadly in a barrel of the type described, wherein:
each projectile includes a sealing portion extending about a tapered anvil portion and loaded into the barrel with high barrel engaging forces by relative forward movement of the sealing portion along the anvil portion;
each projectile includes a hammer member supported for free forward movement into a cavity formed in the exposed rear end of the anvil portion, and
each hammer member being exposed, in use, to its ignited propellant for forward acceleration to impart its energy to the anvil portion by impact so as to jolt the anvil portion from operative sealing engagement with the sealing portion.
In yet a further aspect this invention resides broadly in a barrel of the type described, wherein:
each projectile includes a sealing portion extending about a tapered anvil portion and loaded into the barrel by relative forward movement of the sealing portion along the anvil portion;
each projectile includes a pressure sensitive leverage system connected between the anvil portion and the sealing portion which operates when pressures in the barrel behind the projectile increases beyond a safe operating pressure to lever the sealing portion rearwardly along the anvil portion to a disengaged position.